<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

</body>
<script>
    window.onload=function () {
        let map = new Map([['username',25],[36,'age']])
        console.log(map)
        map.set(78,'haha')
        console.log(map)
        map.delete(78)
        console.log(map)
    }
</script>
</html>
